Levels of testosterone, progesterone, and estrogen will be determined in the umbilical, arterial, and venous blood of intact and decapitated fetuses of both sexes in the same litter and in the mother at 60, 70, 80, 90, 100, and 110 days of gestation in the pig. Gestation length will be determined for litters with both decapitated and intact fetuses. Gestation length will be determined for hybrids between sheep and barbados, and between goats and Barbados. Relaxin levels will be determined in sows with and without fetuses, with and without corpora lutea, and at various stages of gestation after both normal and induced parturition.